Fatty acids from phytoplankton

Abstract

This invention relates to a new process for making fatty acids directly from a feedstock consisting of phytoplankton in water without the need to a) thermally separate, dewater and dry the phytoplankton, and b) extract the immobilized lipids. Our method is much less expensive than the current practice of making fatty acids from phytoplankton, because we bypass the costly and energy intensive operations associated with a) dewatering and drying the biomass, and b) extracting the immobilized lipids. As such, this invention greatly enhances the economic viability of making biofuels and bioproducts from phytoplankton.

What is claimed is: 
     
       1. A continuous process for the production of fatty acids from phytoplankton, said process comprising:
 a) Pressurizing a concentrated slurry with the weight content of the biomass from 5 wt % to 20 wt % to a pressure between 20 and 200 bar; 
 b) performing thermal hydrolysis on the slurry stream using steam as the heat source to convert the immobilized lipids into free fatty acids of varying lengths at temperatures ranging from 200 to 700° C.; 
 c) recovering the heat of the system by interchanging the hydrolysis product with the incoming slurry stream; 
 d) depressurizing the hydrolysis product stream in a separator to release the cooled fatty acids from the depleted slurry; 
 e) feeding the cooled fatty acids stream to a distillation tower for purification; 
 f) feeding the depleted slurry comprisinq the deoiled phytoplankton biomass and water containing glycerol and other water solubles into the solids-liquid filter; 
 g) separating the leftover biomass from the glycerin and water stream by means of filtration; and 
 h) spray-dryinq the biomass for use as a food ingredient for animal feed. 
 
     
     
       2. The process as set forth in  claim 1 , wherein the weight content of the biomass in the slurry ranges from less than 1 wt % up to 15 wt %. 
     
     
       3. The process according to  claim 1 , wherein the biomass slurry is concentrated to between 5 wt % and 20 wt % by means of a crossflow filtration system and recycling the water. 
     
     
       4. The process according to  claim 1 , wherein the temperature depends upon the physical and chemical properties of the phytoplankton that is being processed, and the weight percentage content of the biomass in the slurry. 
     
     
       5. The process according to  claim 1 , wherein hydrogen equivalent to 1.5 wt % of the fatty acid content in the phytoplankton is injected along with the high pressure steam in order to support the hydrogenation reactions. 
     
     
       6. The process as set forth in  claim 1 , wherein a tubular configuration is designed for operation in the cocurrent flow mode, the preheated incoming slurry, the recycled fatty acid product and the injected steam all move in the same direction. 
     
     
       7. The process according to  claim 1 , wherein the slurry consisting of phytoplankton in water does not need to be significantly dewatered and/or dried. 
     
     
       8. The process as set forth in  claim 1 , wherein there is no need to extract the immobilized lipids in order to make fatty acids. 
     
     
       9. The process as set forth in  claim 1  that includes a horizontal hairpin hydrolysis reactor with or without internal static mixers. 
     
     
       10. The process as set forth in  claim 1  that includes a vertical pipe hydrolysis reactor with internal static mixers. 
     
     
       11. The process as set forth in  claim 1  that includes a vertical hairpin hydrolysis reactor with or without internal static mixers. 
     
     
       12. The process as set forth in  claim 1  that includes a multi-stage progressively expanding fluidized bed hydrolysis reactor. 
     
     
       13. The process according to  claim 1 , wherein about 10 wt % of the fatty acid product from the tail end of the process is added to the preheated slurry stream to promote the reaction. 
     
     
       14. The process according to  claim 1  that includes the addition of a solid particulate fluidizing media to enable operation in a backmix mode, wherein the fluidizing media is an inert substance or a base/alkaline heterogeneous catalyst that serves to accelerate the reaction. 
     
     
       15. The process wherein a flocculant is or is not selectively added into the crude fatty acid separator, depending upon the action required and environmental considerations, and the flocculant is either a chemical compound, or a natural biodegradable polymeric substance selected from a group consisting of polyaspartic acid, chitosan or sodium alginate. 
     
     
       16. The process as set forth in  claim 1 , wherein the depleted slurry from the separator containing the deoiled phytoplankton biomass and water containing glycerol and other waste solubles is also drawn out of the separator and the depleted slurry is continuously pumped into a solids-liquid filter that affects the following separations:
 a) A dilute stream consisting of water, glycerol and other water solubles is pumped back; 
 b) The concentrated deoiled wet biomass is sent into a spray dryer, after which this product is bagged and shipped for use as animal food ingredient. 
 
     
     
       17. The process as set forth in  claim 1 , wherein the major impurity content in the crude fatty acid product, C 24.9 H 38.8 O 3 NS 0.1  is the nitrogen compound which is represented by indole, C 8 H 7 N which with a purity of about 99.62 wt % is recovered at the overhead of the distillation column. 
     
     
       18. The process as set forth in  claim 1 , wherein the trace amount of sulfur content in the crude fatty acid product, C 24.9 H 38.8 O 3 NS 0.1  just forms hydrogen sulfide in the hydrolysis reactor and leaves the system.